The invention concerns a pen comprising an applicator tip, a chamber for receiving the applicator tip in a rest position, wherein the chamber has a first through opening through which the applicator tip passes for moving from the rest position into an operative position, and a closure for closing the first through opening.
Pens of the above-indicated kind are known, for example from US No 2004/0265035 A1. In that arrangement the closure which is in the fashion of a sliding door is disposed within the chamber. The sealing function results from a wedge-shaped configuration. More specifically, upon closure, the wedge-shaped part is drawn between two walls. Such a wedging configuration, for closure and even more for opening, requires the application of a considerable amount of force which has to be applied by pressure on the sliding door. In that situation buckling of the sliding door which is of a wall configuration is inevitable. It can also not be suppressed by the sliding door being guided in a gap. At least buckling cannot be prevented into the space where the sliding door has a slot for the applicator tip to pass therethrough.
U.S. Pat. No. 4,759,640 discloses a pen which, for closing the through opening of the chamber, has a pair of flaps (plastic material portions) which are formed integrally with the chamber. They are disposed within the chamber. So that the delicate writing tips do not touch the surfaces of those flaps upon activation/deactivation of the pen (by a pusher mechanism), complicated and expensive encapsulation of the ink reservoir used in the pen (it urges the flaps open) and precise geometrical matching of the portions which are in contact with each other are necessary.
In the pen in accordance with U.S. Pat. No. 6,033,141 the closure is in the form of an elastic, annular, inwardly curved, slotted seal which is disposed within the chamber. Activation/deactivation of the pen can be effected by a pusher mechanism or by a rotary mechanism, wherein the applicator tip is in direct contact with the seal when passing through the through opening because it has to press the seal open. Besides contamination of the seal that also suffers from the disadvantage that the applicator tip is mechanically stressed at each change in its operating condition, at the peripheral surface thereof. That is increasingly the case, the harder the seal. If the seal is made softer, there is the threat of losses of plasticisers in the seal material.
The object of the invention is to develop the pen known from US No 2004/0265035 A1 in such a way that adverse effects in relation to the closure when changing the operating condition thereof are avoided and nonetheless satisfactory sealing of the chamber in the rest condition is achieved.
In accordance with the invention the specified object is attained in that the closure is on an outside of the chamber.
In other words, in accordance with the invention, the chamber is sealed off from the outside and not from the inside, as is the case in US No 2004/0265035 A1. That design configuration has considerable mechanical advantages in terms of a change in the operating condition. In addition, in the case of an outwardly disposed closure, it is easier to ensure a reliable sealing function.